As shown in FIG. 1, a combined chip, consisting essentially of a power switch 10, such as a MOSFET, and an integrated circuit control chip 4 mounted directly on a source electrode 13 of the power switch 10 by an adhesive 191, is known. In the example shown in FIG. 1, the adhesive 191 is an electrically conductive adhesive that also serves to couple the bottom electrode 5 of the control chip 4 directly to the source electrode 13 of the power switch 10. Alternatively, it is known to use an adhesive 191 that is electrically insulating, repositioning the electrode 5 to the same surface of the control chip 4 as the other electrodes 7, 9. Then, the electrode 5 must be electrically coupled to the source electrode 13 by any conventional process, such as by a wire bonding process. Such a combined chip may be packaged by surface mounting the drain electrode 11 of the MOSFET 10 on a printed circuit board 6 (a contact pad of which is partially shown), electrically connecting the drain of the MOSFET 10 to other electronic components by wire traces, for instance. However, a disadvantage of mounting a conventional combined chip directly to a PCB is that thermal management of the power switch 10 is limited by the presence of the PCB adjacent to the combined chip.
Also, conventional power factor correction circuits connect a separately packaged power switch with a separately packaged diode, such that the drain electrode of the power switch, such as a MOSFET 10, is electrically connected to the anode of the diode. However, such an architecture requires inventory and supply management, thermal management and electrical contacts for each of the separately packaged power devices, as both the power switch and the diode produce heat. Also, separately packaging the components and integrating the components in an electronic circuit requires a substantial amount of space for making electrical connections between the separately packaged component parts.
In addition, a conventional diode die is configured to have a wire bondable anode electrode on one side of the diode die and a solderable cathode electrode on the opposite side of the diode die. The anode electrode is wire bonded to one pin of a lead frame. The cathode electrode, which is solderable, is soldered to a copper pad of the lead frame, and the copper pad is electrically connected to another pin of the lead frame. Then, the pad, the diode die and a portion of the pins are packaged by encapsulation, such as in an epoxy resin encapsulant, to protect the diode die, allowing the packaged diode die to be connected to an external electronic circuit, such as a printed circuit board (PCB).